mapnik/bindings/python/mapnik_projection.cpp

/*****************************************************************************
 * 
 * This file is part of Mapnik (c++ mapping toolkit)
 *
 * Copyright (C) 2006 Artem Pavlenko, Jean-Francois Doyon
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 *
 *****************************************************************************/
//$Id$

//boost
#include <boost/version.hpp>
#include <boost/python.hpp>

// mapnik
#include <mapnik/coord.hpp>
#include <mapnik/projection.hpp>

using mapnik::projection;

struct projection_pickle_suite : boost::python::pickle_suite
{
    static boost::python::tuple
    getinitargs(const projection& p)
    {
        using namespace boost::python;
        return boost::python::make_tuple(p.params());
    }
};

namespace {
    mapnik::coord2d forward_pt(mapnik::coord2d const& pt, 
                            mapnik::projection const& prj)
    {
        double x = pt.x;
        double y = pt.y;
        prj.forward(x,y);
        return mapnik::coord2d(x,y);
    }
    
    mapnik::coord2d inverse_pt(mapnik::coord2d const& pt, 
                            mapnik::projection const& prj)
    {
        double x = pt.x;
        double y = pt.y;
        prj.inverse(x,y);
        return mapnik::coord2d(x,y);
    }
   
   mapnik::Envelope<double> forward_env(mapnik::Envelope<double> const & box,
                                    mapnik::projection const& prj)
   {
      double minx = box.minx();
      double miny = box.miny();
      double maxx = box.maxx();
      double maxy = box.maxy();
      prj.forward(minx,miny);
      prj.forward(maxx,maxy);
      return mapnik::Envelope<double>(minx,miny,maxx,maxy);
   }
   
   mapnik::Envelope<double> inverse_env(mapnik::Envelope<double> const & box,
                                    mapnik::projection const& prj)
   {
      double minx = box.minx();
      double miny = box.miny();
      double maxx = box.maxx();
      double maxy = box.maxy();
      prj.inverse(minx,miny);
      prj.inverse(maxx,maxy);
      return mapnik::Envelope<double>(minx,miny,maxx,maxy);
   }
   
}

void export_projection ()
{
    using namespace boost::python; 

    class_<projection>
        ("Projection", "Represents a map projection.",
         init<optional<std::string const&> >
         (
#if BOOST_VERSION >= 103500
          (arg("self"), arg("proj4_string")),
#endif
          "Constructs a new projection from its PROJ.4 string representation.\n"
          "\n"
          "The parameterless version of this constructor is equivalent to\n"      
          "   Projection('+proj=latlong +ellps=WGS84')\n"
          "\n"
          "The constructor will throw a RuntimeError in case the projection\n"
          "cannot be initialized."))
        .def_pickle(projection_pickle_suite())
        .def ("params", make_function(&projection::params,
                                      return_value_policy<copy_const_reference>()
#if BOOST_VERSION >= 103500
                                      , arg("self")
#endif
                                      ),
              "Returns the PROJ.4 string for this projection.")
        .add_property ("geographic", &projection::is_geographic,
                       "This property is True if the projection is a geographic projection\n"
                       "(i.e. it uses lon/lat coordinates)")
        ;
    
    def("forward_",&forward_pt);
    def("inverse_",&inverse_pt);
    def("forward_",&forward_env);
    def("inverse_",&inverse_env);
    
}